ES2211314A1 - Improved resistance welding device - Google Patents

Abstract

The invention relates to an improved resistance welding device. The inventive device comprises an electrode which can move in a support assisted by a spring, a gas cylinder or an expansion element. In this way, upon compression, the movement of the electrode enables the welding time to be sufficiently long such as to be effective without altering the movement cycle of the press in which it is installed. The aforementioned support comprises one or more columns and the sliding electrode is supported by one of said columns. Moreover, the rod of the electrode is housed inside a positioner which can also be moved axially and which receives the small part to be welded by means of a channel. The positioner is made from an insulating material, preferably a ceramic material, and comprises clips which support the part until it is pushed by the rod of the electrode through a lower window for welding.

Description

Improved device for welding by resistance.

Object of the invention

The present invention patent application It aims at registering a perfected device of resistance welding that incorporates notable innovations and advantages over current tools and existing tools for resistance welding of small metal parts and Similar.

More specifically, the new invention comprises a tooling that presents an electrode for welding small parts and the like inside transfer machines or presses Rotary among other applications. The device comprises a mechanism consisting of a mobile electrode in an assisted support by a spring, gas cylinder or compression element, allowing that the welding time span is sufficiently great for it to be effective, without altering the movement cycle of the press in which it is installed. This device is is subject by fast anchoring and acts in coordination with a conventional electrode arranged in the lower matrix. The device can also be used in multi-purpose clamps robots and other machines.

Background of the invention

Resistance welding of metal parts Small is used a lot in different industries. Is applicable for superficial union of parts and in the welding of elements laminar to join.

The classic welding application consists of placement of two pieces between two electrodes by pressing with a defined effort when passing an electric current defined in a predetermined time between the two electrodes. The considerable resistance that exists between the surfaces in contact of the two pieces and the high current passing produces a high heat that melts the local material, thus realizing the welding.

On many occasions two pieces of different size, such as a nut on the surface of a sheet of a certain dimension. The large piece is usually positioned underneath and the small one is loaded by hand, by means of shuttles or pistons on the large one before pressing with the electrodes both parts and solder.

In this welding method, the parameters of circulation time of the electric current and the pressure exerted by the electrodes on the parts to be welded.

Turn in the case of wanting to introduce a step welding in a progressive press machine or station transfer, this must be done at the end of the process and not in a intermediate position, as it would be more logical. This is because during the pressing cycle a pair of electrodes facing not are in a position to carry out the resistance the necessary time With the right pressure. This problem is commonly solved. by fixing the pieces to be joined by riveting or Similary. In fact, the riveting operation is adapted to the cycle of ascension and descent of the matrices in a progressive press, without However, a rivet has a low tensile strength and zero torsion resistance.

Description of the invention

The perfected device for welding by resistance object of the present registry, it is characterized because comprises an electrode of the set of two that form a clamp and which allows its operation as an intermediate welding step in a progressive press machine or transfer stamping machine or automated drawing. However, the use is not ruled out. of said device in robot clamps and other mechanisms susceptible to its use.

The device mainly seeks to obtain two advantages, consisting in achieving sufficient pressure welding for the precise time without the cycle of the press is altered with arrests to perform said welding and automatic placement of the pieces to be welded on the plate or sheet that is embedded or stamped.

In effect the device forms a set of welding together with another electrode, holding the parts to be welded and which allows the circulation of welding current to its through. Each of the electrodes is fixed in one of the matrices or matrix holders facing the press.

The device consists of a body base that is attached to the matrix or matrix holder, said body has one or several parallel columns, although in principle the case with two columns, being on one of said movable columns the electrode and on the other column the coupling element intermediate of the positioning piece. Said electrode is forced by a rear expander element, such as a spring or a gas cylinder. The tip of the electrode is housed in the inside of a floating supported ceramic positioner body on the other column. At the end of this body is the small piece to be welded (for example a nut) arranged subject for welding and facing a lower window. When lowering the machine the positioner makes contact with the lower part (for example a sheet on which the nut is placed), compressing it against the lower electrode. These positioner places the window through which the nut or piece to be welded directly on the surface of the lower part in its correct position. The Continued compression causes the electrode tip advance through the body of the body that holds the nut approaching the nut and supported on said rear expander element. When the advance of the press compresses the electrode against the nut or piece to be welded shifts its position against the bottom plate and said expander element prints enough pressure between the parts to be welded to perform welding by the current flow When the press goes back the electrode is removed first and then the positioner, leaving the two pieces (plate and nut) properly welded and joined.

This device is designed for welding in a very short period of time, corresponding with which the electrode is pressed against the piece with sufficient force according to the setting of the subsequent expansion For this, it is planned that the device welding current supplier operate with a high high intensity and frequency.

The electrode comprises a base body with a through hole in relation to the column on which it is ready. Enter the hole or housing for a guide of the electrode and the column there is an insulating sliding sleeve, for example of ceramic material, or similar. Said electrode presents in its rear end the corresponding connection with the cable electrical and in its previous part a corresponding stem with the inside of it, which establishes contact with the piece a weld and with the subsequent expansion element. The body of electrode is water cooled by an inner channel. TO in turn, the axial rod is preferably air cooled, through holes or grooves through which forced air circulates, for example, in order to avoid spills of liquid on the matrix. It is also planned that in the case of uses extremes in which a lot of heat is generated in the electrode, all the cooling either by liquid in full, either with water or with suitable coolants. The stem is attached to the electrode body permanently or removably, since either by a morse cone, a cylindrical anchor or other means of analog mounting.

The positioner meets two premises fundamental, you must place the small piece in the right place for welding and must accommodate the electrode rod slider Taking into account that said electrode heats up ostensibly this positioner is manufactured in a material that is temperature resistant and also be electrical insulator around the electrode, such as a ceramic or similar. The positioner comprises in its lower part the exit window of the small piece to be welded, with the appropriate dimensions. Aside there is a window that communicates with the gutter through which automated parts supplied, existing in front a sensor that determines when the piece is placed in its position to start the welding or lowering process of the press. The part is held until the electrode rod is push towards the distal window using side clips or a similar system.

The union of the positioner on the column in the that moves is done by a coupling piece intermediate. This piece also serves as a support for the entrance of the parts supply gutter and regulator automatism of your entry. Between this coupling piece and the column is an expansion element that determines the pressure to take off the upper body respectively. The column presents a inner hole in which there is a spring or expansion cylinder faced within the coupling piece. In turn, the coupling piece has a pivot, or limiter support of run, housed in a lateral groove of the column in order to Avoid turns and limit the maximum run. It is planned to enter the column and the coupling piece there is a bushing or insulating and antifriction element.

The whole set is subject to the matrix or matrix holder by means of a quick joint system, such as easily removable staples or claws.

Since the device is intended for use fully automatically and without assistance you can submit several sensors, such as the aforementioned presence sensor of small piece to be welded inside the positioner, or the automatic supply of parts at the entrance of the gutter, among others.

To complete the description that follows will perform and in order to help a better understanding of their characteristics, is accompanied by the present specification, of a set of figures, in an illustrative and non-limiting way, where they represent the most significant details of the invention.

Brief description of the designs

Figure 1. Shows an elevation view partially sectioned from the device.

Figure 2. Shows an elevation view of the column that supports the electrode.

Figure 3. Shows an elevation view semi-selected column that supports the coupling piece intermediate.

Figure 4. Shows a bottom view of the piece intermediate coupling.

Figure 5. Shows a sectioned elevation view of the intermediate coupling piece.

Figure 6. Shows a sectioned view transversely of the intermediate coupling piece.

Figure 7. Shows a plan view of the body of the electrode.

Figure 8. Shows a sectioned elevation view of the electrode body.

Figure 9. Shows a sectioned elevation view of the positioner.

Figure 10. Shows a view of a section transverse positioner.

Figure 11. Shows an elevation view of the electrode rod

Figure 12. Shows a sectioned elevation view of the electrode rod, showing the passageways of air.

Figure 13. Shows a section view cross section of the electrode rod showing the pipes of air passage.

Figure 14. Shows a semi-selected view of a welding detail with the workpiece pressed by the rod against the plate to be welded and in a slightly position previous.

Description of a preferred embodiment

In view of the commented figures and agree with the numbering adopted, you can see in them a preferred, but not limiting embodiment of the invention, the which comprises a support body (1) with two columns (3 and 4) parallel, among which is an expansion element (11) in parallel arrangement. This body (1) presents in its part later a plate (2) suffridera and on both sides chamfered for fastening by staples (24) or the like. Over one column (3) is an electrode (5 and 6) comprising a body (5) with a fixing hole with a bushing (10) insulating slide. The body (5) of the electrode presents in a end an anchor (9) with the connection cable with the unit electric welding power (not shown) and on the other end a rod (6) pressure descendant. Inside of body (5) of the electrode is a circuit (7) for the passage of liquid cooling with its corresponding inlet (8) and exit. In turn, the stem (6) has a series of holes and air cooling passage slots (29). Said rod (6) it is arranged coaxial with the expansion element (11) existing in the support body (1) and partially housed in the inner axial hole (13) of a positioner (12). On the other column (4) is an intermediate coupling part (19). At the end of said column (4) is a hole (30) blind, in which there is a spring (25) or expansion element forced against said coupling part (19). In turn, the column (4) has a sliding groove (26) on one side of a pivot (27) existing in the coupling part (19), suitable to delimit the relative displacement between the two. This piece (19) of displacement has a pin on its side (23) quick clamping of the nut supply channel (18) in its housing and in the previous part a hollow of accommodation of the positioning element (12). Said positioning element (12) it is fixed in turn by a second pin (22). The piece (19) coupling has a sliding bushing (20) of fixation on the column (4).

The positioning element (12) comprises a axial inner hole (13) in which the rod (6) is housed of the electrode and in which the small part (31) to be welded is received from a side window (15) embedded to the mouth (17) of the gutter (18). On both sides of the axial hole (13) of the positioner (12), and at the height of the input window (15) of the gutter (18) there are windows in which they are emerging two clips (16) holding the small part (31) when it enters from said channel (18). The axial hole (13) presents in the lower end a part exit window (14) (31) small to be welded pushed by the rod (6) of the electrode against the plate (32) to be joined, in collaboration with the lower electrode (28). On one side of the positioner (12) the coupling part (19) has associated a sensor (21) of presence of part (31) to automation.

Claims (11)

1. Device perfected for resistance welding, automatic operation and attachable to the matrix or matrix holder of a press with progressive matrix or press with transfer matrix among others, characterized in that it comprises a base body (1), from which one or more several columns (3 and 4) parallel, existing on at least one of the columns (3) an electrode (5 and 6) related to a pole of a generator (not shown) of electric welding current and in at least one column ( 4) a positioner (12) of the small piece (31) to be welded, the electrode (5 and 6) being inserted in said positioner (12) for compression of said piece (31) to be welded onto the plate (32) or lower part to be welded against a second electrode (28); and because it comprises a spring or expansion element (11) in a position posterior to the rod (6) of the electrode and coaxial with its axis of motion, operatively capable of exerting the compression force in the weld; and because it comprises an intermediate coupling part (19) between the positioner (12) and the column (4). 2. Device perfected for resistance welding, according to claim 1, characterized in that the electrode comprises a body (5) with a through hole or guide housing of the column (3) in sliding form; and because the body (5) has a corresponding internal channeling with a liquid cooling circuit (7) with its corresponding inlet and outlet (8); and because the body (5) of the electrode has a stem (6) partially inserted into the positioner (12) and arranged coaxially with the expansion element (11), operatively suitable for penetration. 3. Improved device for resistance welding, according to claims 1 and 2, characterized in that the rod (6) of the electrode has holes or grooves (29) for air cooling. 4. Improved device for resistance welding, according to claims 1 and 2, characterized in that in an alternative embodiment the cooling of the rod is by liquid. 5. Device perfected for resistance welding, according to claims 1 and 2, characterized in that the positioner (12) comprises an axial hole (13) of passage of the rod (6), presenting a lower placement window (14) of the part (31) when welding and a side window (15) of entry of the part (31) to be welded, embedded at the entrance (17) of an automatic supply gutter (18); and because the positioner (12) comprises on both sides of the axial hole (13) respective clips (16) for holding the piece (31) to be welded by springs or the like; and because the positioner (12) comprises, adjacent to one of its walls, a part presence sensor (21) to be welded in the correct position inside the axial hole (13). 6. Device perfected for resistance welding, according to claim 5, characterized in that the axial through hole (13) has a guide (not shown) for displacement of the rod (6). 7. Device perfected for resistance welding, according to claims 1 and 5, characterized in that the positioner (12) is made of an insulating material of the electric current and heat resistant. 8. Improved device for resistance welding, according to claims 1 and 5, characterized in that the intermediate coupling part (19) comprises a housing or hollow of the 12 column (4) through which it is movable; and because the column (4) comprises a blind inner hole (30) at its free end, an expander element (25) existing inside said hole, such as a spring or a gas cylinder facing the part (19) coupling for separation; and because the column (4) comprises, on one side of its contour, a longitudinal groove (26) of determined length in which there is a limiting slide pivot (27), emanating from the intermediate coupling part (19) suitable for determine a maximum travel stroke; and because the intermediate coupling part (19) comprises a bushing (20) sliding around the column (4). Device perfected for resistance welding, according to claims 1, 5 and 8, characterized in that the intermediate coupling part (19) comprises a housing for the supply channel (18) for small parts (31) to be welded inside the positioner (12); and because it comprises the mouth (17) of the gutter facing the side window (15) entering the axial hole (13) of the positioner; and because it comprises a pin (23) for fixing said channel or similar fixing means. 10. Device perfected for resistance welding, according to claims 1, 5 and 8, characterized in that the intermediate coupling part (19) comprises a pin (22) or means for quickly securing the positioner (12) for rapid extraction. 11. Device perfected for resistance welding, according to claim 1, characterized in that the body (1) comprises a coupling or shape of the base body suitable for fastening by a quick fixing means, such as staples (24) , to the matrix, matrix holder or tool on which the device is placed; and because said base body (1) comprises in its rear part a plate (2) suffering from contact with the surface on which it is coupled, operatively capable of receiving compression stresses in welding.